Deleted workflow reappears after daemon restart

[nimitbhardwaj]

Description: When a workflow is deleted via the web dashboard or API, it disappears from the UI. However, after restarting the openfang daemon/gateway, the deleted workflow reappears. This happens because the workflow's .json file is not removed from ~/.openfang/workflows/ when the workflow is deleted.

Expected Behavior: A workflow should remain deleted after deletion, even after daemon restart.

Steps to Reproduce:

1. Create a new workflow via the web dashboard
2. Verify the workflow's .json file exists in ~/.openfang/workflows/
3. Delete the workflow via the web dashboard
4. Verify the workflow disappears from the dashboard UI
5. Check that the .json file still exists in ~/.openfang/workflows/ (BUG: file not deleted)
6. Restart the openfang daemon/gateway
7. Observe that the deleted workflow reappears in the dashboard

Root Cause:

• remove_workflow() in crates/openfang-kernel/src/workflow.rs:235-238 only removes from in-memory HashMap, does NOT delete the .json file
• Workflow creation in crates/openfang-api/src/routes.rs:985-1001 correctly persists to disk
• On startup, load_workflows_from_dir() in crates/openfang-kernel/src/kernel.rs:4634-4650 loads all .json files, re-importing "deleted" workflows